The eggs look like they are too wet to me. Have you considered putting some egg crate into the tub to lift the eggs out of the substrate?

http://www.homedepot.com/p/24-in-x-4...6#.UVEOZr_qo_s

I wouldn't put anti-fungal powder into the tub, or on the eggs. Just get them out of the wet substrate and see if that resolves this issue.